Rotary compressor

Abstract

A rotary compressor includes a first cylinder, a first piston and a drive shaft. The drive shaft includes a first eccentric portion, a first shaft portion rotatably supported by a first bearing, and a first coupling portion coupling the first shaft portion with the first eccentric portion. The first piston is fitted to the first eccentric portion. The first shaft portion has a cylindrical shape coaxial with the rotational center axis. Re1−e1<R1. Re1 is a radius of the first eccentric portion. R1 is a radius of the first shaft portion. e1 is an eccentricity of the first eccentric portion. An outer surface of the first coupling portion does not extend radially out of the outer surface of the first eccentric portion. A circumferentially extending groove is formed at an end of an inner peripheral surface of the first piston on a first coupling portion side in the axial direction of the drive shaft.

What is claimed is: 
     
       1. A rotary compressor comprising:
 a first cylinder; 
 a first piston that has a cylindrical shape, the first piston being configured to revolve along an inner wall surface of the first cylinder, and the first piston forming a first compression chamber configured to compress a fluid between the first piston and the inner wall surface of the first cylinder; and 
 a drive shaft that is rotatable, the drive shaft including
 a first eccentric portion that is eccentric in a first direction with respect to a rotational center axis and to which the first piston is fitted, 
 a first shaft portion that is rotatably supported by a first bearing formed on a first end plate to close one end face of the first cylinder, and the first shaft portion having a cylindrical shape coaxial with the rotational center axis of the drive shaft, and 
 a first coupling portion that couples the first shaft portion with the first eccentric portion, the first coupling portion being disposed inside the first end plate, 
 
 the drive shaft being configured to satisfy R e1 −e 1 <R 1 , R e1  being a radius of the first eccentric portion, R 1  being a radius of the first shaft portion, and e 1  being an eccentricity of the first eccentric portion, 
 the first coupling portion being formed such that an outer surface of the first coupling portion does not extend beyond an outer surface of the first eccentric portion in a radial direction of the drive shaft, the first coupling portion being configured to satisfy H C1 <H P1 , H C1  being a height of the first coupling portion in an axial direction of the drive shaft, and H P1  being a height of the first piston, and 
 a circumferentially extending groove being formed at an end of an inner peripheral surface of the first piston on a first coupling portion side in the axial direction of the drive shaft, the groove being provided in order to avoid contact between the inner peripheral surface of the first piston and the first shaft portion when the first piston is disposed on an outer peripheral side of the first coupling portion and the inner peripheral surface of the first piston being disposed outside an outer peripheral surface of the first eccentric portion in the radial direction of the drive shaft. 
 
     
     
       2. The rotary compressor of  claim 1 , wherein
 the groove is formed in a circumferential part of the inner peripheral surface of the first piston. 
 
     
     
       3. The rotary compressor of  claim 2 , further comprising
 a first blade extending from the first piston toward the first cylinder, and the first blade partitioning the first compression chamber into a low-pressure chamber on a suction port side and a high-pressure chamber on a discharge port side, 
 the first piston being configured to swing with respect to a central axis of the first eccentric portion while revolving along the inner wall surface of the first cylinder along with rotation of the drive shaft, and 
 the groove being formed within a half circumference of the suction port side from a placement position of the first blade in a circumferential direction of the first piston. 
 
     
     
       4. The rotary compressor of  claim 1 , further comprising:
 a second cylinder; and 
 a second piston that has a cylindrical shape, the second piston being configured to revolve along an inner wall surface of the second cylinder, and the second piston forming a second compression chamber to compress a fluid between the second piston and the inner wall surface of the second cylinder, 
 the drive shaft further including
 a second eccentric portion that is provided on a side opposite to the first coupling portion of the first eccentric portion in the axial direction, and the second eccentric portion being eccentric in a second direction opposite to the first direction with respect to the rotational center axis and to which the second piston is fitted, 
 a second coupling portion that couples the first eccentric portion with the second eccentric portion, and 
 a second shaft portion
 that continuously extends from a side of the second eccentric portion opposite to the second coupling portion in the axial direction, 
 to which an electric motor that drives the drive shaft to rotate is coupled, 
 that is rotationally supported by a second bearing formed on a second end plate to close one end face of the second cylinder, and 
 that has a cylindrical shape coaxial with the rotational center axis of the drive shaft, and 
 
 
 the first shaft portion being formed to have a smaller diameter than the second shaft portion. 
 
     
     
       5. The rotary compressor of  claim 4 , further comprising
 an intermediate end plate
 that has a middle hole to allow the drive shaft to pass therethrough, 
 that blocks other end faces of the first cylinder and the second cylinder between the first cylinder and the second cylinder, and 
 that slides on other end faces of the first piston and the second piston, 
 
 the first eccentric portion having a smaller diameter than the second eccentric portion. 
 
     
     
       6. The rotary compressor of  claim 4 , wherein
 the drive shaft being configured to satisfy R e2 −e 2 ≥R 2 , R e2  is a radius of the second eccentric portion, R 2  is a radius of the second shaft portion, and e 2  is an eccentricity of the second eccentric portion. 
 
     
     
       7. The rotary compressor of  claim 1 , wherein
 the first coupling portion includes a reinforcement portion at which the outer surface of the first coupling portion protrudes beyond an outer surface of the first shaft portion in the radial direction of the drive shaft but does not protrude beyond the outer surface of the first eccentric portion in the radial direction of the drive shaft, the reinforcement portion being disposed inside the first end plate. 
 
     
     
       8. The rotary compressor of  claim 7 , wherein
 a portion of the first end plate disposed between the first bearing and the first eccentric portion of the drive shaft is recessed toward the first bearing to accommodate the reinforcement portion. 
 
     
     
       9. A rotary compressor comprising:
 a first cylinder; 
 a first piston that has a cylindrical shape, the first piston being configured to revolve along an inner wall surface of the first cylinder, and the first piston forming a first compression chamber configured to compress a fluid between the first piston and the inner wall surface of the first cylinder; and 
 a drive shaft that is rotatable and comprises
 a first eccentric portion that is eccentric in a first direction with respect to a rotational center axis and to which the first piston is fitted, 
 a first shaft portion that is rotatably supported by a first bearing formed on a first end plate to close one end face of the first cylinder, and the first shaft portion having a cylindrical shape coaxial with the rotational center axis of the drive shaft, and 
 a first coupling portion that couples the first shaft portion with the first eccentric portion, 
 
 the drive shaft being configured to satisfy R e1 −e 1 <R 1 , R e1  being a radius of the first eccentric portion R 1  being a radius of the first shaft portion, and e 1  being an eccentricity of the first eccentric portion, 
 the first coupling portion being formed such that an outer surface thereof does not extend beyond an outer surface of the first eccentric portion in a radial direction of the drive shaft, the first coupling portion being configured to satisfy H C1 <H P1 , H C1  being a height of the first coupling portion in an axial direction of the drive shaft, and H P1  being a height of the first piston, and 
 a circumferentially extending groove being formed at an end of an inner peripheral surface of the first piston on a first coupling portion side in the axial direction of the drive shaft, the groove satisfying H>H P1 −H C1 , H being a height of the groove in the axial direction of the drive shaft, and the groove having a cross-sectional shape with which the groove is capable of containing a part of the first shaft portion extending out of the outer surface of the first eccentric portion as viewed in the axial direction of the drive shaft. 
 
     
     
       10. The rotary compressor of  claim 9 , wherein
 the groove is formed in a circumferential part of the inner peripheral surface of the first piston. 
 
     
     
       11. The rotary compressor of  claim 10 , further comprising
 a first blade extending from the first piston toward the first cylinder, and the first blade partitioning the first compression chamber into a low-pressure chamber on a suction port side and a high-pressure chamber on a discharge port side, 
 the first piston being configured to swing with respect to a central axis of the first eccentric portion while revolving along the inner wall surface of the first cylinder along with rotation of the drive shaft, and 
 the groove being formed within a half circumference of the suction port side from a placement position of the first blade in a circumferential direction of the first piston. 
 
     
     
       12. The rotary compressor of  claim 9 , further comprising:
 a second cylinder; and 
 a second piston that has a cylindrical shape, the second piston being configured to revolve along an inner wall surface of the second cylinder, and the second piston forming a second compression chamber to compress a fluid between the second piston and the inner wall surface of the second cylinder, 
 the drive shaft further including
 a second eccentric portion that is provided on a side opposite to the first coupling portion of the first eccentric portion in the axial direction, and the second eccentric portion being eccentric in a second direction opposite to the first direction with respect to the rotational center axis and to which the second piston is fitted, 
 a second coupling portion that couples the first eccentric portion with the second eccentric portion, and 
 a second shaft portion
 that continuously extends from a side of the second eccentric portion opposite to the second coupling portion in the axial direction, 
 to which an electric motor that drives the drive shaft to rotate is coupled, 
 that is rotationally supported by a second hearing formed on a second end plate to close one end face of the second cylinder, and 
 that has a cylindrical shape coaxial with the rotational center axis of the drive shaft, and 
 
 
 the first shaft portion being formed to have a smaller diameter than the second shaft portion. 
 
     
     
       13. The rotary compressor of  claim 12 , further comprising
 an intermediate end plate
 that has a middle hole to allow the drive shaft to pass therethrough, 
 that blocks other end faces of the first cylinder and the second cylinder between the first cylinder and the second cylinder, and 
 that slides on other end faces of the first piston and the second piston, 
 
 the first eccentric portion having a smaller diameter than the second eccentric portion. 
 
     
     
       14. The rotary compressor of  claim 10 , wherein
 the drive shaft being configured to satisfy R e2 −e 2 ≥R 2 , R e2  is a radius of the second eccentric portion, R 2  is a radius of the second shaft portion, and e 2  is an eccentricity of the second eccentric portion. 
 
     
     
       15. The rotary compressor of  claim 9 , wherein
 the first coupling portion is disposed inside the first end plate. 
 
     
     
       16. The rotary compressor of  claim 15 , wherein
 the first coupling portion includes a reinforcement portion at which the outer surface of the first coupling portion protrudes beyond an outer surface of the first shaft portion in the radial direction of the drive shaft but does not protrude beyond the outer surface of the first eccentric portion in the radial direction of the drive shaft, the reinforcement portion being disposed inside the first end plate. 
 
     
     
       17. The rotary compressor of  claim 16 , wherein
 a portion of the first end plate disposed between the first bearing and the first eccentric portion of the drive shaft is recessed toward the first bearing to accommodate the reinforcement portion.